1. Field of the Invention
The present invention relates to a projector, and more particularly to a projector having a light source lamp.
2. Description of the Related Art
A projector for forming an optical image corresponding to image information by optically processing the light emitted from a light source lamp is conventionally known (e.g., refer to JP-A-2001-215618).
FIG. 9 is an exploded perspective view showing a projection section and a light source section of a conventional projector, and FIG. 10 is a perspective view of a casting of the conventional projector shown in FIG. 9. FIG. 11 is an enlarged perspective view of a light tunnel and its vicinities of the conventional projector shown in FIG. 9. FIG. 12 is a perspective view of a light tunnel clip of the conventional projector shown in FIG. 9. FIG. 13 is an enlarged perspective view of a positioning boss of a lamp case of the conventional projector shown in FIG. 9. FIG. 14 is a perspective view of a light source lamp of the conventional projector shown in FIG. 9. FIG. 15 is a cross-sectional view for explaining the relationship between the emitted light from the light source lamp and the light tunnel. First, referring to FIGS. 9 to 15, a description will be given of the structure of the conventional projector.
As shown in FIG. 9, the conventional projector has a projection section 102 and a light source section 103 provided inside the apparatus. A casting 104 is provided in the projection section 102. As shown in FIG. 10, this casting 104 has a lens mounting portion 141, a light tunnel fitting portion 142, and a guide portion 143. The lens mounting portion 141 is provided with a circular lens-attaching hole portion 141a. Further, the light tunnel fitting portion 142 is provided with a slot portion 142a having side surfaces and a bottom surface inclined by a predetermined angle, two positioning bosses 142b, and two threaded holes 142c. Furthermore, the guide portion 143 is provided with three cylindrically shaped portions 143b each having a guide hole 143a. 
As shown in FIG. 9, a projection lens 105 for projecting an image onto a screen or the like is fitted in the circular lens-attaching hole portion 141a of the casting 104. Further, a tubular light tunnel 106 is fixed in the slot portion 142a (see FIG. 10) of the casting 104 by means of a light tunnel clip 107, as shown in FIG. 11. The light tunnel 106 has an inlet portion 106a through which the light from the light source section 103 (see FIG. 9) enters. The light tunnel 106 has the function of shaping the form of the light which entered the inlet portion 106a. Further, in order to shape the light into a rectangular form, the light tunnel 106 is constructed to form a tubular tetrahedron by means of four reflecting mirrors, and such that a mirror section is disposed inside it.
In addition, as shown in FIGS. 11 and 12, the light tunnel clip 107 has leaf spring-shaped first pressing portions 107a for pressing an upper surface of the light tunnel 106 and leaf spring-shaped second pressing portions 107b for pressing one side surface thereof. Further, guide holes 107c and screw hole portions 107d are respectively provided in regions of the light tunnel clip 107 corresponding to the positioning bosses 142b and the threaded holes 142c (see FIG. 10) of the casting 104. In addition, an opening 107e is provided in a region of the light tunnel clip 107 corresponding to the inlet portion 106a of the light tunnel 106. Further, the positioning bosses 142b of the casting 104 are respectively inserted in the two guide holes 107c of the light tunnel clip 107. Furthermore, the light tunnel clip 107 is attached to the casting 104 by means of screws 142d through the two screw hole portions 107d of the light tunnel clip 107. In consequence, the light tunnel 106 is fixed by the pressing forces of the first pressing portions 107a and the second pressing portions 107b of the light tunnel clip 107.
In addition, as shown in FIG. 9, a lamp case holder 108 is provided in the light source section 103. This lamp case holder 108 is provided with two threaded holes 108a. A lamp case 109 is accommodated in the lamp case holder 108. This lamp case 109 is provided with two screw hole portions 109a. Further, the lamp case 109 is attached to the lamp case holder 108 by means of screws 108b through the two screw hole portions 109a of the lamp case 109.
In addition, positioning bosses 109b for positioning the lamp case 109 with respect to the casting 104 are provided on a surface of the lamp case 109 on the projection section 102 side. Each positioning boss 109b of the lamp case 109 has a substantially cruciform shape as viewed in the direction of arrow P shown in FIG. 13. In addition, the positioning bosses 109b of the lamp case 109 are disposed at positions respectively corresponding to the guide holes 143a (see FIGS. 9 and 10) of the three cylindrically shaped portions 143b of the casting 104. As the lamp case 109 is fixed to the lamp case holder 108 with the screws 108b in a state in which the three positioning bosses 109b of the lamp case 109 are respectively inserted in the guide holes 143a, the lamp case 109 is fixed in a state of being positioned with respect to the casting 104.
As shown in FIG. 9, a light source lamp 110 is fitted in the lamp case 109. This light source lamp 110 is formed by a light source 110a and a concave reflector 10b, as shown in FIGS. 14 and 15. Further, as the light 110c produced by the light source 110a is reflected by the concave reflector 110b, the light is focused into a central portion of the inlet portion 106a of the light tunnel 106 fitted in the casting 104.
Here, with the conventional projector using the light source lamp 110, when the operating time of the projector reaches a predetermined time, the power of the light source lamp 110 declines, so that it is necessary to replace the light source lamp 110. In the case where the light source lamp 110 of the conventional projector is replaced, a user needs to replace the light source lamp 110 including the lamp case 109 shown in FIG. 9.